Impact of Zeta Potential on Copper Adsorption of Surface-Modified Hydroxyapatites Derived From Fish Bone Waste

Zeta potential emerges as a crucial parameter in understanding particle surface charges and assessing the stability of colloidal systems. It also serves as a key indicator in determining electrostatic interactions between surfaces and ions. In this study, hydroxyapatite (HA) derived from fish waste was functionalized with histidine (HA4) and 4-Aminohippuric acid (HA5), and their surface properties and heavy metal ion (Cu2+) adsorption capacities were investigated. Zeta potential measurements performed after surface modification showed that both modifications induced a negative charge on the surface. The surface modified with histidine exhibited a zeta potential in the range of -3.48 to -5.09 mV, while the surface modified with 4-Aminohippuric acid demonstrated a higher negative charge. Adsorption experiments revealed that HA5 exhibited a superior Cu2+ binding capacity of 9.96 mg/g compared to HA4 (9.52 mg/g). The findings indicate that zeta potential and the presence of functional groups on the surface play a significant role in the retention of heavy metal ions. These results suggest that modified fish bone surfaces can serve as effective and sustainable adsorbents for environmental applications.